1. Field of the Invention
This invention relates in general to earth boring bits and in particular to an insert type rock bit of the rolling cutter type having specially shaped cutting tips.
2. Description of the Prior Art
Rock bits using sintered tungsten carbide inserts or compacts with cutting tips having a generally wedge or chisel-shaped configuration are used for drilling soft and medium formations. Various configurations for wedge-shaped inserts are shown in U.S. Pat. No. 3,442,342 issued to Hughes Tool Company. Inserts of this type have a pair of symmetrical flanks that converge to a rounded crest. The inserts are interferringly secured in holes drilled normal to the cutter surface. Consequently as the cutter rotates, the crest initially contacts the formation at a time when the longitudinal axis of the insert is non-perpendicular with respect to the hole bottom. Bending stresses are thus generated in the inserts, tending to cause breakage.